1. Field of the Invention
The present invention relates to a display device having a backlight device. More particularly, the present invention relates to an electron emission unit that is arranged in a backlight panel and emits electrons toward a phosphor layer.
2. Description of the Related Art
A backlight panel includes a phosphor layer and an anode at an interior side of a front substrate, and electron emission regions and driving electrodes at an interior side of a rear substrate. The front and rear substrates are sealed to each other at their peripheries using a sealing member, and the inner space between the first and second substrates is exhausted to form a vacuum chamber.
The driving electrodes include cathode electrodes arranged with a gap along a direction of the rear substrate and gate electrodes arranged between the cathode electrodes in parallel therewith. In addition, an electron emission region is formed at a side of the cathode electrode facing the gate electrode.
When a driving voltage is applied to the cathode electrodes and the gate electrodes, an electric field is formed near the electron emission regions by a voltage difference between the cathode electrodes and the gate electrodes, and accordingly, electrons are emitted from the electron emission regions. The emitted electrons are accelerated by a high voltage (anode voltage) applied to the anode and collide on the phosphor layer so as to excite the phosphor layer whereby visible light is emitted.
Uniform luminance and efficiency are important characteristics of the backlight panel. It is preferred that uniform luminance is realized throughout an entire active area of the backlight panel. Efficiency (in luminance and/or power consumption) of the backlight panel is enhanced by realizing high luminance with low power consumption.
According to a conventional backlight panel, electrons are emitted in one direction from the cathode electrode to the gate electrode. Therefore, electrons are not uniform on the phosphor layer, and the luminance uniformity is not high. In addition, since the entire electron emission regions are exposed to the anode electric field, a diode emission in which electrons are emitted due to the anode electric field may occur. Therefore, the anode voltage can be increased within a very limited level, and thus the luminance of the backlight panel can be increased within a very limited level.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.